BDNF and depressive disorder: Stress causes reduction of brain derived neurotrophic factor (BDNF) expression and the mechanistic target of rapamycin (mTOR) in synapse, consequently contributing to the loss and atrophy of specific synapse in the brain regions implicated in depression, particularly the PFC and the hippocampus (Marsden, 2013; Abelaira et al., 2014; Vose and Stanton, 2017).